NUMERICAL INVESTIGATION FOR THE ENHANCEMENT OF THE AERODYNAMIC CHARACTERISTICS OF AN AEROFOIL BY USING A GURNEY FLAP

Abstract

Numerical investigation was carried out to determine the effect of a Gurney Flap on NACA
0012 aerofoil performance with emphasis on Unmanned Air Vehicles applications. The study examined
different configurations of Gurney Flaps at high Reynolds number of Re = 3.6 × 105

in order to determine
the optimal configuration. The Gurney flap was tested at different heights, locations and mounting angles.
Compared to the clean aerofoil, the study found that adding the Gurney Flap increased the maximum lift
coefficient by19%, 22%, 28%, 40% and 45% for the Gurney Flap height of 1%C, 1.5%C, 2%C, 3%C and
4%C respectively, C represents the chord of the aerofoil. However, it was also found that increasing the
height of the gurney beyond 2%C leads to a decrease in the overall performance of the aerofoil due to the
significant increase in drag penalty. Thus, the optimal height of the Gurney flap for the NACA 0012 aerofoil
was found to be 2%C as it improves the overall performance of the aerofoil by 21%. As for the location, it
was found that the lifting-enhanced effect of the gurney flap decreases as it is shifted towards the leading
edge. Thus the optimal location of the Gurney Flap mounting was found to be at the trailing edge or at
distances smaller than 10%C. The Gurney flap was also tested at different mounting angles of -45, 90 and
+45 degrees and it was found that the Gurney flap at +45 mounting angle leads to the optimal performance of
the aerofoil